Earth`s Cryosphere, 2018, Vol. XXII, № 4, p. 68-74
CHANGES IN PROPERTIES AND STATE OF COAL EXPOSED TO FREEZE-THAW WEATHERING: EVIDENCE FROM THERMALLY INDUCED ACOUSTIC EMISSION
E.A. Novikov, V.L. Shkuratnik, M.G. Zaytsev, R.O. Oshkin
National University of Science and Technology “MISiS”, Moscow Mining Institute (MGI), 4, Leninskiy ave., Moscow, 119049, Russia; ftkp@mail.ru, e.novikov@misis.ruAcoustic emission responses of water-saturated lignite and hard coal samples exposed to cyclic freezing and thawing have been studied as a function of the number of loading cycles, at different stages of freeze-thaw weathering, including prefailure. It is suggested to use an acoustic emission ratio to track the weathering history of coal and to assess the dependence of the weathering rate on pore water pH. The revealed acoustic emission patterns are applicable to predict the effect of weathering on the oxidation of coal which reduces its calorific value and poses risks of spontaneous combustion.
Acoustic emission, fossil coal, freezing, thawing, freeze-thaw weathering, experiment, express testing